<template>
  <div class="app-container">
    <!--查询表单-->
    <el-form :inline="true" size="small" class="demo-form-inline">

      <!-- 所属分类：级联下拉列表 -->
      <!-- 一级分类 -->
      <el-form-item label="课程类别">
        <el-select
          v-model="searchObj.subjectParentId"
          placeholder="请选择"
          @change="subjectLevelOneChanged">
          <el-option
            v-for="subject in subjectList"
            :key="subject.id"
            :label="subject.title"
            :value="subject.id"/>
        </el-select>

        <!-- 二级分类 -->
        <el-select v-model="searchObj.subjectId" placeholder="请选择">
          <el-option
            v-for="subject in subjectLevelTwoList"
            :key="subject.id"
            :label="subject.title"
            :value="subject.id"/>
        </el-select>
      </el-form-item>

      <!-- 标题 -->
      <el-form-item>
        <el-input v-model="searchObj.title" placeholder="课程标题"/>
      </el-form-item>
      <!-- 讲师 -->
      <el-form-item>
        <el-select
          v-model="searchObj.teacherId"
          placeholder="请选择讲师">
          <el-option
            v-for="teacher in teacherList"
            :key="teacher.id"
            :label="teacher.name"
            :value="teacher.id"/>
        </el-select>
      </el-form-item>

      <el-button type="primary" size="small" icon="el-icon-search" @click="fetchData">查询</el-button>
      <el-button type="default" size="small" @click="resetData">清空</el-button>
    </el-form>

    <!-- 表格 -->
    <el-table :data="courseList" border stripe>

      <el-table-column label="#" width="50">
        <template slot-scope="scope">
          {{ (page - 1) * limit + scope.$index + 1 }}
        </template>
      </el-table-column>

      <el-table-column label="封面" width="200" align="center">
        <template slot-scope="scope">
          <img :src="scope.row.cover" alt="scope.row.title" width="100%">
        </template>
      </el-table-column>
      <el-table-column label="课程信息">
        <template slot-scope="scope">
          <a href="">{{ scope.row.title }}</a>
          <p>
            分类：{{ scope.row.subjectParentTitle }} > {{ scope.row.subjectTitle }}
          </p>
          <p>
            课时：{{ scope.row.lessonNum }} /
            浏览：{{ scope.row.viewCount }} /
            付费学员：{{ scope.row.buyCount }}
          </p>
        </template>
      </el-table-column>
      <el-table-column label="讲师" width="100" align="center">
        <template slot-scope="scope">
          {{ scope.row.teacherName }}
        </template>
      </el-table-column>
      <el-table-column label="价格(元)" width="100" align="center" >
        <template slot-scope="scope">
          <el-tag v-if="Number(scope.row.price) === 0" type="success">免费</el-tag>
          <!-- 前端解决保留两位小数的问题 -->
          <!-- <el-tag v-else>{{ Number(scope.row.price).toFixed(2) }}</el-tag> -->
          <!-- 后端解决保留两位小数的问题，前端不用处理 -->
          <el-tag v-else>{{ scope.row.price }}</el-tag>
        </template>
      </el-table-column>
      <el-table-column prop="status" label="课程状态" width="100" align="center" >
        <template slot-scope="scope">
          <el-tag :type="scope.row.status === 'Draft' ? 'warning' : 'success'">{{ scope.row.status === 'Draft' ? '未发布' : '已发布' }}</el-tag>
        </template>
      </el-table-column>
      <el-table-column label="创建时间" width="120" align="center">
        <template slot-scope="scope">
          {{ scope.row.gmtCreate.substr(0, 10) }}
        </template>
      </el-table-column>

      <el-table-column label="操作" width="300" align="center">
        <template slot-scope="scope">
          <router-link :to="'/course/info/'+scope.row.id">
            <el-button type="primary" size="mini" icon="el-icon-edit">修改</el-button>
          </router-link>
          <router-link :to="'/course/chapter/'+scope.row.id">
            <el-button type="primary" size="mini" icon="el-icon-edit">编辑大纲</el-button>
          </router-link>
          <el-button type="danger" size="mini" icon="el-icon-delete" @click="removeById(scope.row.id)">删除</el-button>
        </template>
      </el-table-column>
    </el-table>

    <!-- 分页组件 -->
    <el-pagination
      :current-page="page"
      :total="total"
      :page-size="limit"
      :page-sizes="[5, 10, 20, 30, 40, 50, 100]"
      style="padding: 30px 0; text-align: center;"
      layout="total, sizes, prev, pager, next, jumper"
      @size-change="changePageSize"
      @current-change="changeCurrentPage"
    />
  </div>
</template>

<script>
import course from '@/api/course'
import teacher from '@/api/teacher'
import subject from '@/api/subject'

export default {
  data() {
    return {
      page: 1,
      total: 0,
      limit: 10,
      courseList: [],
      searchObj: {
        subjectId: ''// 解决查询表单无法选中二级类别
      },
      subjectList: [],
      teacherList: [],
      subjectLevelTwoList: []
    }
  },
  created() {
    this.getList()
    this.initTeacherList()
    this.initSubjectList()
  },
  methods: {
    // 每页记录数改变，size：回调参数，表示当前选中的“每页条数”
    changePageSize(size) {
      this.limit = size
      this.getList()
    },
    // 改变页码，page：回调参数，表示当前选中的“页码”
    changeCurrentPage(page) {
      this.page = page
      this.getList()
    },
    initSubjectList() {
      subject.getNestedTreeList().then(result => {
        this.subjectList = result.data.items
      })
    },
    initTeacherList() {
      teacher.list().then(result => {
        this.teacherList = result.data.items
      })
    },
    removeById(id) {
      this.$confirm('是否要删除该课程及相关信息？', '警告', {
        confirmButtonText: '确定',
        cancelButtonText: '取消',
        type: 'warning'
      }).then(() => {
        course.removeById(id).then(result => {
          this.getList()
          this.$message.success(result.message)
        })
      }).catch(err => {
        if (err === 'cancel') {
          this.$message({
            type: 'info',
            message: '已取消删除'
          })
        }
      })
    },
    resetData() {
      this.searchObj = {}
      this.subjectLevelTwoList = []
      this.getList()
    },
    fetchData() {
      this.getList()
    },
    subjectLevelOneChanged(value) {
      this.subjectList.forEach(item => {
        if (item.id === value) {
          this.subjectLevelTwoList = item.children
          this.searchObj.subjectId = ''
        }
      })
    },
    getList() {
      course.getPageList(this.page, this.limit, this.searchObj).then(result => {
        this.courseList = result.data.rows
        this.total = result.data.total
      })
    }
  }
}
</script>

<style lang="scss" rel="stylesheet/scss">

</style>
